They are incredibly durable as far as fire, G forces and damage.
2,000F and 100G
The CVR must record 2 hours of data, and the FDR must record 25 hours of data.
They have been found after many years under water with retrievable data.
Taking damage:
Five torture tests check the durability of black box design. one unit must survive all the tests:
1. Impact shock: Tests the ability of the recorder to survive the impact of a crash. The recorder is fired from an air cannon at 500 feet per second into a barrier 2.5 feet from the muzzle. the impact simulates a force of 3,400 gs, or 3,400 times the force of gravity.
2. Penetration resistance: The unit must withstand flying debris. A 1/4” pin at the end of a 500 lb. weight is dropped onto the recorder from a height of 10 ft.
3. Static crush: A hydraulic press puts 5,000 lbs. of pressure on the unit seven times for a total of five minutes.
4. Fire: The crash survival module must withstand a temperature of 2,000 degrees F for 30 minutes. The heat is so intense that the unprotected interface electronics melt away in the first five minutes. Propane torches are used to incinerate the unit because a jet fuel fire is too difficult to control for more than 10 minutes.
5. Fluid immersion: The same recorder that has been put through the previous tests is soaked for 48 hours in each of the different fluids found on a jetliner, including jet fuel, kerosene, hydraulic fluid and firefighting chemicals.
SOURCES: Loral Data Systems; Universal Avionics Systems Corp.; The American Society of Mechanical Engineers
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